a) Field of the Invention
The present invention relates to zoom lens system which has a wide field angle.
b) Description of the Prior Art
In the present days, there is a remarkable trend manufacture, as commercial products developed with a new concept, fully automated cameras which incorporate zoom lens systems having high vari-focal ratios. These zoom lens systems having high vari-focal ratios always have wide field angles or high telephoto ratios.
The conventional zoom lens systems have field angles on the order of 2 .omega.=63.degree. at wide positions thereof. Further, out of zoom lens systems which have low vari-focal ratios, there are known those which have field angles on the order of 2 .omega.=84.degree. as exemplified by the zoom lens system disclosed by Japanese Patent Kokai Publication No. Hei 2-284,109.
Further, conventional super wide angle zoom lens systems are known only as interchangeable lens systems which are to be used with single-lens reflex cameras. However, the lens system proposed by Japanese Patent Kokai Publication No. Hei 2-135,312 is a compact zoom lens system which is usable with lens shutter cameras.
Each of the lens systems mentioned above cannot correct aberrations sufficiently favorably since it was obtained simply by modifying an exsisting zoom lens system so as to have a wider field angle. In other words, each of the zoom lens systems mentioned above is a telephoto type zoom lens system which is modified so as to have a shorter focal length or a wider focal length and is insufficient in optical performance thereof.